An electrostatic coating system is known in which workpieces moved by a conveyor through a coating zone are charged by inducing a voltage from a charged wire adjacent the path of the workpiece support. A circular disc collector on the support travels through the field adjacent the charged wire. Swinging or tilting of the workpiece support changes the distance between the collector and the charged wire. This varies the induced voltage on the workpiece and may adversely affect the quality of the coating. If the charge collector or other portions of the workpiece support approach the charged wire too closely, sparking may occur.